“Eating turkey makes you sleepy due to tryptophan.”

That familiar post-holiday meal drowsiness often gets blamed on the star of the feast: turkey. The idea that turkey's tryptophan content is solely responsible for a "food coma" is a widespread misconception, particularly around Thanksgiving in North America. This myth likely gained traction due to the observed sleepiness many people experience after a large, celebratory meal where turkey is prominently featured. It's an easy connection to make, attributing a common feeling to a specific, well-known component of the meal.

While it's true that turkey does contain tryptophan, an essential amino acid, its role in inducing sleepiness is often overstated. Tryptophan is a precursor to serotonin, a neurotransmitter, which is then converted into melatonin, a hormone that regulates sleep. However, the amount of tryptophan in a typical serving of turkey is not significantly higher than in many other common foods, like chicken, cheese, or nuts. Moreover, the presence of other amino acids in turkey actually competes with tryptophan for absorption into the brain, further limiting its sleep-inducing effect. Research indicates that you would need to consume an unrealistic amount of turkey for its tryptophan content alone to have a noticeable sedative effect.

The real culprit behind that sleepy feeling after a big meal is usually the sheer volume of food consumed, especially when it's rich in carbohydrates and fats, and sometimes accompanied by alcohol. Eating a large meal diverts a significant amount of blood flow to the digestive system, temporarily reducing blood flow to the brain and other parts of the body, which can lead to a feeling of lethargy. Carbohydrates, in particular, can facilitate the absorption of tryptophan into the brain by increasing insulin levels, but this effect is still more pronounced with carb-heavy meals than with turkey itself. People continue to believe the myth because the correlation between eating turkey and feeling sleepy is strong in their personal experience, even if the causation is misattributed.